Some systems include the use of a harmonic oscillator. For example, in inductive sensing applications, an “LC tank” is driven to produce an oscillation signal whose frequency vanes with distance to a nearby conductive object. The frequency of the oscillation signal is a function of the distance to the object. Such systems are useful as distance measurement sensors.
Due to manufacturing tolerances, stress (pressure) and temperature gradients, mismatches between circuit components (which otherwise should have identical characteristics) may introduce error in the amplitude control of the oscillation signal. Static mismatches, which do not change with time, can be corrected with various techniques such as calibration, differential measurements, etc. However, such techniques are not particularly useful to correct for mismatches in component characteristics that vary with time, such as temperature gradients and flicker noise.